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IEVref: | 112-01-28 | ID: | |

Language: | en | Status: Standard | |

Term: | value of a quantity | ||

Synonym1: | quantity value [Preferred] | ||

Synonym2: | value [Preferred] | ||

Synonym3: | |||

Symbol: | |||

Definition: | number and reference together expressing magnitude of a quantity
Note 1 to entry: According to the type of reference, the value of a quantity is either:
- a product of a number and a unit of measurement (the unit one is generally omitted for quantities of dimension one, as in examples f and g):
a) Length of a given rod: 5,34 m or 534 cm b) Mass of a given body: 0,152 kg or 152 g c) Curvature of a given arc: 112 m ^{–1}, expressed in words by "one hundred and twelve per metre"d) Celsius temperature of a given sample: –5 °C e) Electric impedance of a given circuit element at a given frequency, where j is the imaginary unit: (7,5 + 3,2 j) Ω f) Refractive index of a given sample of glass: 1,32 g) Mass fraction of cadmium in a given sample of copper: 3 µg/kg or 3 × 10 ^{–1}h) Molality of Pb ^{2+}in a given sample of water: 1,76 mmol/kg - a number and a reference to a measurement procedure:
Rockwell C hardness of a given sample: 43,5 HCR - a number and a reference material:
Arbitrary amount-of-substance concentration of lutropin in a given sample of human blood plasma (WHO International Standard 80/552 used as a calibrator): 5,0 IU/l, where "IU" stands for "WHO International Unit"
In the first case, the value of a quantity Note 2 to entry: The number can be complex (see example e in Note 1 to entry). Note 3 to entry: The value of a quantity can be presented in more than one way (see examples a, b, and g in Note 1 to entry). Note 4 to entry: In the case of vector or tensor quantities, each component has a value, and the same for the magnitude of a vector quantity. Example:
force acting on a given particle, e.g. in Cartesian components | ||

Publication date: | 2019-01 | ||

Source: | ISO/IEC Guide 99:2007, 1.19, modified – Transposition of the English preferred term and synonym. Combination of EXAMPLE 1 to EXAMPLE 10 in a new Note 1 to entry, and deletion of NOTE 1. | ||

Replaces: | 112-01-28:2010-01 | ||

Internal notes: | |||

CO remarks: | |||

TC/SC remarks: | |||

VT remarks: | |||

Domain1: | |||

Domain2: | |||

Domain3: | |||

Domain4: | |||

Domain5: |

Note 1 to entry: According to the type of reference, the value of a quantity is either:

- a product of a number and a unit of measurement (the unit one is generally omitted for quantities of dimension one, as in examples f and g):
a) Length of a given rod: 5,34 m or 534 cm

b) Mass of a given body: 0,152 kg or 152 g

c) Curvature of a given arc: 112 m

^{–1}, expressed in words by "one hundred and twelve per metre"d) Celsius temperature of a given sample: –5 °C

e) Electric impedance of a given circuit element at a given frequency, where j is the imaginary unit: (7,5 + 3,2 j) Ω

f) Refractive index of a given sample of glass: 1,32

g) Mass fraction of cadmium in a given sample of copper: 3 µg/kg or 3 × 10

^{–1}h) Molality of Pb

^{2+}in a given sample of water: 1,76 mmol/kg - a number and a reference to a measurement procedure:
Rockwell C hardness of a given sample: 43,5 HCR

- a number and a reference material:
Arbitrary amount-of-substance concentration of lutropin in a given sample of human blood plasma (WHO International Standard 80/552 used as a calibrator): 5,0 IU/l, where "IU" stands for "WHO International Unit"

In the first case, the value of a quantity *Q* is generally denoted {*Q*}[*Q*] where {*Q*} is the numerical value and [*Q*] is the unit of measurement.

Note 2 to entry: The number can be complex (see example e in Note 1 to entry).

Note 3 to entry: The value of a quantity can be presented in more than one way (see examples a, b, and g in Note 1 to entry).

Note 4 to entry: In the case of vector or tensor quantities, each component has a value, and the same for the magnitude of a vector quantity. Example:

force acting on a given particle, e.g. in Cartesian components

(*F*_{x}; *F*_{y}; *F*_{z}) = (–31,5; 43,2; 17,0) N